Simulation of the process of self-oscillations in a supersonic jet impinging on a Hartmann tube

The fluctuating process of the interaction between a supersonic jet and a hollow obstacle is numerically investigated. The calculations are performed using the Godunov method. In the calculations both the physical parameters (Mach number and exit-to-ambient jet pressure ratio) and the geometric parameters (longitudinal and transverse tube dimensions and the nozzle/tube spacing) are varied. The fluctuating processes of two types are revealed, namely, the high- and low-frequency processes, differing in the occurring flow pattern. It is concluded that in the case of supersonic jets the fluctuation occurrence is due to the excitation of the natural oscillations of a cylindrical resonator.